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Retired Document

Important: This sample code may not represent best practices for current development. The project may use deprecated symbols and illustrate technologies and techniques that are no longer recommended.

Relevant replacement documents include:

http://developer.apple.com/library/mac/samplecode/sc2195/Introduction/Intro.html#//apple_ref/doc/uid/DTS40013969

PublicUtility/CAGuard.cpp

/*

 <codex>

 <abstract>CAGuard.h</abstract>

 <\codex>

*/

//==================================================================================================

//  Includes

//==================================================================================================

//  Self Include

#include "CAGuard.h"

#if TARGET_OS_MAC

    #include <errno.h>

#endif

//  PublicUtility Inludes

#include "CADebugMacros.h"

#include "CAException.h"

#include "CAHostTimeBase.h"

//==================================================================================================

//  Logging

//==================================================================================================

#if CoreAudio_Debug

//  #define Log_Ownership       1

//  #define Log_WaitOwnership   1

//  #define Log_TimedWaits      1

//  #define Log_Latency         1

//  #define Log_Errors          1

#endif

//#warning      Need a try-based Locker too

//==================================================================================================

//  CAGuard

//==================================================================================================

CAGuard::CAGuard(const char* inName)

    CAMutex(inName)

#if Log_Average_Latency

    ,mAverageLatencyAccumulator(0.0),

    mAverageLatencyCount(0)

#endif

#if TARGET_OS_MAC

    OSStatus theError = pthread_cond_init(&mCondVar, NULL);

    ThrowIf(theError != 0, CAException(theError), "CAGuard::CAGuard: Could not init the cond var");

#elif TARGET_OS_WIN32

    mEvent = CreateEvent(NULL, true, false, NULL);

    ThrowIfNULL(mEvent, CAException(GetLastError()), "CAGuard::CAGuard: Could not create the event");

#endif

CAGuard::~CAGuard()

#if TARGET_OS_MAC

    pthread_cond_destroy(&mCondVar);

#elif TARGET_OS_WIN32

    if(mEvent != NULL)

        CloseHandle(mEvent);

#endif

void    CAGuard::Wait()

#if TARGET_OS_MAC

    ThrowIf(!pthread_equal(pthread_self(), mOwner), CAException(1), "CAGuard::Wait: A thread has to have locked a guard before it can wait");

    mOwner = 0;

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::Wait: thread %p is waiting on %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

    OSStatus theError = pthread_cond_wait(&mCondVar, &mMutex);

    ThrowIf(theError != 0, CAException(theError), "CAGuard::Wait: Could not wait for a signal");

    mOwner = pthread_self();

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::Wait: thread %p waited on %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

#elif TARGET_OS_WIN32

    ThrowIf(GetCurrentThreadId() != mOwner, CAException(1), "CAGuard::Wait: A thread has to have locked a guard before it can wait");

    mOwner = 0;

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::Wait: thread %lu is waiting on %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

    ReleaseMutex(mMutex);

    HANDLE theHandles[] = { mMutex, mEvent };

    OSStatus theError = WaitForMultipleObjects(2, theHandles, true, INFINITE);

    ThrowIfError(theError, CAException(GetLastError()), "CAGuard::Wait: Could not wait for the signal");

    mOwner = GetCurrentThreadId();

    ResetEvent(mEvent);

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::Wait: thread %lu waited on %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

#endif

bool    CAGuard::WaitFor(UInt64 inNanos)

    bool theAnswer = false;

#if TARGET_OS_MAC

    ThrowIf(!pthread_equal(pthread_self(), mOwner), CAException(1), "CAGuard::WaitFor: A thread has to have locked a guard be for it can wait");

    #if Log_TimedWaits

        DebugMessageN1("CAGuard::WaitFor: waiting %.0f", (Float64)inNanos);

    #endif

    struct timespec theTimeSpec;

    static const UInt64 kNanosPerSecond = 1000000000ULL;

    if(inNanos >= kNanosPerSecond)

        theTimeSpec.tv_sec = static_cast<UInt32>(inNanos / kNanosPerSecond);

        theTimeSpec.tv_nsec = static_cast<UInt32>(inNanos % kNanosPerSecond);

    else

        theTimeSpec.tv_sec = 0;

        theTimeSpec.tv_nsec = static_cast<UInt32>(inNanos);

    #if Log_TimedWaits || Log_Latency || Log_Average_Latency

        UInt64  theStartNanos = CAHostTimeBase::GetCurrentTimeInNanos();

    #endif

    mOwner = 0;

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::WaitFor: thread %p is waiting on %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

    OSStatus theError = pthread_cond_timedwait_relative_np(&mCondVar, &mMutex, &theTimeSpec);

    ThrowIf((theError != 0) && (theError != ETIMEDOUT), CAException(theError), "CAGuard::WaitFor: Wait got an error");

    mOwner = pthread_self();

    #if Log_TimedWaits || Log_Latency || Log_Average_Latency

        UInt64  theEndNanos = CAHostTimeBase::GetCurrentTimeInNanos();

    #endif

    #if Log_TimedWaits

        DebugMessageN1("CAGuard::WaitFor: waited  %.0f", (Float64)(theEndNanos - theStartNanos));

    #endif

    #if Log_Latency

        DebugMessageN1("CAGuard::WaitFor: latency  %.0f", (Float64)((theEndNanos - theStartNanos) - inNanos));

    #endif

    #if Log_Average_Latency

        ++mAverageLatencyCount;

        mAverageLatencyAccumulator += (theEndNanos - theStartNanos) - inNanos;

        if(mAverageLatencyCount >= 50)

            DebugMessageN2("CAGuard::WaitFor: average latency  %.3f ns over %ld waits", mAverageLatencyAccumulator / mAverageLatencyCount, mAverageLatencyCount);

            mAverageLatencyCount = 0;

            mAverageLatencyAccumulator = 0.0;

    #endif

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::WaitFor: thread %p waited on %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

    theAnswer = theError == ETIMEDOUT;

#elif TARGET_OS_WIN32

    ThrowIf(GetCurrentThreadId() != mOwner, CAException(1), "CAGuard::WaitFor: A thread has to have locked a guard be for it can wait");

    #if Log_TimedWaits

        DebugMessageN1("CAGuard::WaitFor: waiting %.0f", (Float64)inNanos);

    #endif

    //  the time out is specified in milliseconds(!)

    UInt32 theWaitTime = static_cast<UInt32>(inNanos / 1000000ULL);

    #if Log_TimedWaits || Log_Latency || Log_Average_Latency

        UInt64  theStartNanos = CAHostTimeBase::GetCurrentTimeInNanos();

    #endif

    mOwner = 0;

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::WaitFor: thread %lu is waiting on %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

    ReleaseMutex(mMutex);

    HANDLE theHandles[] = { mMutex, mEvent };

    OSStatus theError = WaitForMultipleObjects(2, theHandles, true, theWaitTime);

    ThrowIf((theError != WAIT_OBJECT_0) && (theError != WAIT_TIMEOUT), CAException(GetLastError()), "CAGuard::WaitFor: Wait got an error");

    mOwner = GetCurrentThreadId();

    ResetEvent(mEvent);

    #if Log_TimedWaits || Log_Latency || Log_Average_Latency

        UInt64  theEndNanos = CAHostTimeBase::GetCurrentTimeInNanos();

    #endif

    #if Log_TimedWaits

        DebugMessageN1("CAGuard::WaitFor: waited  %.0f", (Float64)(theEndNanos - theStartNanos));

    #endif

    #if Log_Latency

        DebugMessageN1("CAGuard::WaitFor: latency  %.0f", (Float64)((theEndNanos - theStartNanos) - inNanos));

    #endif

    #if Log_Average_Latency

        ++mAverageLatencyCount;

        mAverageLatencyAccumulator += (theEndNanos - theStartNanos) - inNanos;

        if(mAverageLatencyCount >= 50)

            DebugMessageN2("CAGuard::WaitFor: average latency  %.3f ns over %ld waits", mAverageLatencyAccumulator / mAverageLatencyCount, mAverageLatencyCount);

            mAverageLatencyCount = 0;

            mAverageLatencyAccumulator = 0.0;

    #endif

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::WaitFor: thread %lu waited on %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

    theAnswer = theError == WAIT_TIMEOUT;

#endif

    return theAnswer;

bool    CAGuard::WaitUntil(UInt64 inNanos)

    bool    theAnswer = false;

    UInt64  theCurrentNanos = CAHostTimeBase::GetCurrentTimeInNanos();

#if Log_TimedWaits

    DebugMessageN2("CAGuard::WaitUntil: now: %.0f, requested: %.0f", (double)theCurrentNanos, (double)inNanos);

#endif

    if(inNanos > theCurrentNanos)

#if Log_Errors

        if((inNanos - theCurrentNanos) > 1000000000ULL)

            DebugMessage("CAGuard::WaitUntil: about to wait for more than a second");

#endif

        theAnswer = WaitFor(inNanos - theCurrentNanos);

    else

#if Log_Errors

        DebugMessageN2("CAGuard::WaitUntil: Time has expired before waiting, now: %.0f, requested: %.0f", (double)theCurrentNanos, (double)inNanos);

#endif

        theAnswer = true;

    return theAnswer;

void    CAGuard::Notify()

#if TARGET_OS_MAC

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::Notify: thread %p is notifying %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

    OSStatus theError = pthread_cond_signal(&mCondVar);

    ThrowIf(theError != 0, CAException(theError), "CAGuard::Notify: failed");

#elif TARGET_OS_WIN32

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::Notify: thread %lu is notifying %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

    SetEvent(mEvent);

#endif

void    CAGuard::NotifyAll()

#if TARGET_OS_MAC

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%p %.4f: CAGuard::NotifyAll: thread %p is notifying %s, owner: %p\n", pthread_self(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), pthread_self(), mName, mOwner);

    #endif

    OSStatus theError = pthread_cond_broadcast(&mCondVar);

    ThrowIf(theError != 0, CAException(theError), "CAGuard::NotifyAll: failed");

#elif TARGET_OS_WIN32

    #if Log_WaitOwnership

        DebugPrintfRtn(DebugPrintfFileComma "%lu %.4f: CAGuard::NotifyAll: thread %lu is notifying %s, owner: %lu\n", GetCurrentThreadId(), ((Float64)(CAHostTimeBase::GetCurrentTimeInNanos()) / 1000000.0), GetCurrentThreadId(), mName, mOwner);

    #endif

    SetEvent(mEvent);

#endif

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